Method for preparation of carborane anions

Abstract

This invention relates to an improved method for making unsubstituted carborane anions and monosubstituted carborane anions of formula: (R—CBn—Hm′)− where n is an integer ranging from 5 to about 11 and m′ is an integer ranging from 5 to 16 where the relative values of n and m′ depend upon the exact structure of the carborane and the presence of a non-hydrogen substituent. m as used herein is an integer ranging from 5 to 16. When R is hydrogen the anion is unsubstituted. When R is a halogen, a phenyl, a substituted phenyl group, such as fluorophenyl group, or any other substituent, the carborane is substituted. The method is particularly useful for preparation of twelve-vertex carborane anions R—CB11H11−, where R is a defined above, and is specifically useful for preparation of the unsubstituted carborane CB11H12-??, where R is H.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is the National Stage of International Application No. PCT / US02 / 10060, filed Apr. 1, 2002, which claims the benefit of U.S. provisional application Ser. No. 60 / 280,243, filed Mar. 30, 2001, which is hereby incorporated by reference to the extent not inconsistent herewith.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]This invention was made with U.S. Government support under National Science Foundation Grant No. 981979. The Government has certain rights in this invention.BACKGROUND OF THE INVENTION[0003]It is generally known that salts of the twelve-vertex carborane anion CB11H12−(I) serve as starting materials for the preparation of partially and fully substituted anions of the type CB11XnH(12−n)− (II, where the substituents X need not be the same). The latter are of considerable interest as relatively inert and weakly nucleophilic anions for applications including, among others, incorporation in ca...

AI Technical Summary

Benefits of technology

[0012]Solvents for the reaction and the addition of cations to the reaction mixture are selected to avoid premature precipitation of borane anions or borane dianions and decreased yields of desired products For example, it is believed that no reaction of B11H14− was observed when 1,4-dioxane was used as the solvent because the disodium salt of B11H132− is barely soluble in this solvent.

Problems solved by technology

Until the present time, the high cost of the starting material, CB11H12−, has discouraged commercial use of these highly promising anions.

As far as we are aware, this starting material is at present sold commercially by only one company (Katchem Ltd., Prague, Czech Republic), and is very expensive.

Currently the anion is produced from an expensive precursor, decaborane, in three steps; the synthesis is difficult to scale up and is performed in small batches.

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